Typically the storage of photons has an analogy to electron storage such as the well known capacitor memory cell. Difficulty in producing such devices has arisen from the physical problems of containing a photon or a stream of photons. To date most approaches for storing photons are either based on the effects of optically bistability or the utilization of long fiber loops.
Devices that utilize the use of optical bistability are both technologically complex and expensive, with much of the early work motivated by the notion that optics could be used to avoid some of the intrinsic speed limitations of electronic storage analogs. These devices rely on electro-optic conversion and hence the storage of an electron. Devices that utilize the use of fiber loops exist in the form of sequential storage pipes used to house a sequential stream of photons flowing in a re-circulating path in a first in first out fashion. These fiber loops are used as delay lines and are typically referred to as “Programmable Photonic Fiber Loop Memory”, A. Dickson et al. Proceedings of the 16th Australian Conference on Optical Future Technology, pp 274–277, 1991.
For future data storage, it is desirable to have a photon storage device as a counter part or replacement for today's analogous electronic memory devices. These should be capable of meeting the high speed data storage requirements expected for the next generation of information processing hardware. In addition to speed, such devices should also meet the expected high storage capacity (bit density) requirements for advanced processing applications. Finally the importance of error reduction from limited alpha emissions as well as radiation hardened capability would be desirable for space exploration.